In a general sense, multiple pistons operating in a common combustion chamber are known in conventionally cranked internal combustion engines from such as a split single cylinder twin piston engine in which two parallel cylinders are siamesed by a common combustion chamber having their pistons linked to a common crank pin. Such existing arrangements employ a differential motion between the pistons because of the common crank which can lead to improved engine scavenging.
In the present invention a plurality of pistons are employed in compressing the charge of a single combustion chamber with particular applicability to radial cylinder machines or rotary machines as disclosed in our International patent applications PCT/AU89/00275 and PCT/AU91/00224 hereinafter referred to as split-cycle machines. The multiple piston single combustion chamber arrangement of the present invention is equally applicable to compressors or pumps as it is to engines.